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A topic used to broadcast a message to all consumers¶

This sample demonstrates how ESB Micro Integrator can be used to implement a publisher-subscriber messaging scenario using RabbitMQ topics. That is, a message publisher can broadcast a message to multiple consumers through the RabbitMQ topic.

As shown below, the publisher proxy in the Micro Integrator will publish messages to a RabbitMQ topic, which multiple subscriber proxies (defined in the Micro Integrator) will consume.

Synapse configurations¶

See the instructions on how to build and run this example.

RabbitMQ Subscriber 1

<?xml version="1.0" encoding="UTF-8"?><proxy xmlns="http://ws.apache.org/ns/synapse" name="TopicSubscriber1" transports="rabbitmq" startOnLoad="true">
  <description/>
  <target>
      <inSequence>
          <log level="custom">
              <property name="Message Received" expression="//Message"/>
          </log>
          <call>
              <endpoint>
                  <http uri-template="http://localhost:8280/employees" method="post"/>
              </endpoint>
          </call>
      </inSequence>
  </target>
  <parameter name="rabbitmq.queue.routing.key">topic1</parameter>
  <parameter name="rabbitmq.exchange.name">amq.topic</parameter>
  <parameter name="rabbitmq.queue.name">queue2</parameter>
  <parameter name="rabbitmq.connection.factory">AMQPConnectionFactory</parameter>
</proxy>

RabbitMQ Subscriber 2

<?xml version="1.0" encoding="UTF-8"?><proxy xmlns="http://ws.apache.org/ns/synapse" name="TopicSubscriber2" transports="rabbitmq" startOnLoad="true">
  <description/>
  <target>
      <inSequence>
          <log level="custom">
              <property name="Message Received" expression="//Message"/>
          </log>
          <call>
              <endpoint>
                  <http uri-template="http://localhost:8280/employees" method="post"/>
              </endpoint>
          </call>
      </inSequence>
  </target>
  <parameter name="rabbitmq.queue.routing.key">topic1</parameter>
  <parameter name="rabbitmq.exchange.name">amq.topic</parameter>
  <parameter name="rabbitmq.queue.name">queue3/parameter>
  <parameter name="rabbitmq.connection.factory">AMQPConnectionFactory</parameter>
</proxy>

RabbitMQ Publisher

<?xml version="1.0" encoding="UTF-8"?><proxy xmlns="http://ws.apache.org/ns/synapse" name="TopicPublisher" transports="http https" startOnLoad="true">
  <description/>
  <target>
      <inSequence>
          <property name="OUT_ONLY" value="true"/>
          <property name="FORCE_SC_ACCEPTED" value="true" scope="axis2"/>
          <send>
              <endpoint>
                  <address uri="rabbitmq:/topic1?rabbitmq.server.host.name=localhost&amp;rabbitmq.server.port=5672&amp;rabbitmq.server.user.name=guest&amp;rabbitmq.server.password=guest&amp;rabbitmq.exchange.name=amq.topic"/>
              </endpoint>
          </send>
      </inSequence></target></proxy>

Build and run¶

Create the artifacts:

Set up ESB Integration Studio.
Create an integration project with an ESB Configs module and an Composite Exporter.
Create the proxy service with the configurations given above.
Enable the RabbitMQ sender and receiver in the Micro-Integrator from the deployment.toml. Refer the configuring RabbitMQ documentation for more information.
Deploy the artifacts in your Micro Integrator.
Make sure you have a RabbitMQ broker instance running.
Create queue1 and queue2 and add bind them in the amq.topic exchange with the routing key topic1.
Publish the following payload to the topic using the publisher proxy (TopicPublisher).
```
<Message>
<Name>John Doe</Name>
<Age>27</Age>
</Message>
```

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